Kai,
No you don't use that much, just enough to get it going and keep it going, besides those caps would blow before the glass would. And the great thing is that you can put both carboys side by side and you don't have to worry about getting one higher thatn the other and risk breaking them.

I'm going to switch to this concept. I'm an auto-siphon guy right now but apparently I need to replace it as when I rack over the last couple batches using it I have a hell of a time with air leaking during the transfer. The center cane of the auto-siphon where you attach the hose may have gotten warped somehow. (hot garage?).

I have been using a similar method for some time now, my exceptions are that I have used a two holed stopper ( instead of a cap) and I use a vacuum pump and a small air compresser instead of mouth power. (depending on direction of flow)
The air compressor is a medical unit 110V and the vacuum pump is from a Ford
F250 diesel truck ( new unit) 12V, I have been lucky that I have the means to do this with out a great expense. Homebrewers are an inventive lot and cheap beyond compare.
And to answer some concerns, no matter what method you use to suck or blow you can transfer fluid up hill as it were.

Kai,
No you don't use that much, just enough to get it going and keep it going, besides those caps would blow before the glass would. And the great thing is that you can put both carboys side by side and you don't have to worry about getting one higher thatn the other and risk breaking them.

i was actually doing something similar by using a double action hand pump to force the beer from one vessel to another. But I thought that if I would use CO2, I may not be able to control the pressure so well and the carboy may explode. I'm not sure if the cap would come off first. Mine were on pretty tight.

i was actually doing something similar by using a double action hand pump to force the beer from one vessel to another. But I thought that if I would use CO2, I may not be able to control the pressure so well and the carboy may explode. I'm not sure if the cap would come off first. Mine were on pretty tight.

Kai

You would still be ok, you dont clamp the hoses on and all you are doing is using the CO2 to push the beer from one vessel to another. I have been doing this for over 10 years and have never had a problem. It really is the easiest and most sanitary way of moving your beer.